@os-team/graphql-transformers

The type-graphql decorator to transform arguments. Contains the most used transformers.

Installation

Install the package using the following command:

yarn add @os-team/graphql-transformers

It is assumed that the type-graphql library is already installed.

Usage

For example, we have the fox entity and 2 files: CreateFoxInput.ts and FoxResolver.ts.

Step 1. Create transformers

import { Field, InputType } from 'type-graphql';
import { trim, toLowerCase } from '@os-team/graphql-transformers';

@InputType()
class CreateFoxInput {
  @Field()
  name!: string;
}

export const createFoxTransformers = {
  name: [trim, toLowerCase],
};

export default CreateFoxInput;

Step 2. Add the @TransformArgs decorator

import { Arg, Mutation, Resolver } from 'type-graphql';
import { TransformArgs } from '@os-team/graphql-transformers';
import Fox from '../../entities/Fox';
import CreateFoxInput, { createFoxTransformers } from './CreateFoxInput';

@Resolver(() => Fox)
class FoxResolver {
  @TransformArgs(createFoxTransformers, { arg: 'input' })
  @Mutation(() => Fox)
  async createFox(@Arg('input') input: CreateFoxInput): Promise<Fox> {
    // The implementation
  }
}

export default FoxResolver;

If you did not specify the arg parameter, the @TransformArgs decorator will transform all the arguments. It can be useful, for example, if you want to transform the connection arguments.

import { Args, Query, Resolver } from 'type-graphql';
import { TransformArgs } from '@os-team/graphql-transformers';
import { ConnectionArgs, createConnectionType } from '@os-team/graphql-utils';
import Fox from '../../entities/Fox';
import FoxConnectionArgs, {
  foxConnectionTransformers,
} from './FoxConnectionArgs';

export const FoxConnection = createConnectionType(Fox);

@Resolver(() => Fox)
class FoxResolver {
  @TransformArgs(foxConnectionTransformers)
  @Query(() => FoxConnection)
  async foxes(@Args() args: FoxConnectionArgs): Promise<Connection<Fox>> {
    // The implementation
  }
}

export default FoxResolver;

Create the custom transformer

You can create your own transformers like this:

import { Transformer } from '../utils/TransformArgs';

const trim: Transformer<string> = (value) => value.trim();

export default trim;

The transformer can only be synchronous.